The present invention relates to a device and a method for determining a corrected offset value.
Adaptive cruise control (ACC) for a vehicle regulates the distance maintained from the vehicle in front as a function of vehicle speed. A method described in German Published Patent Application No. 197 22 947 from this field, whereby, among other things, the future course of a vehicle including an ACC system is taken into account in the ACC regulation. To do so, the future course range of at least one vehicle driving in front is determined, and then a lateral transverse offset is determined in relation to all vehicles detected. In steady-state road surface curvature conditions, i.e., when traveling along a straight route or in an area of constant curvature in a turn, the future driving corridor is easily determined using the conventional method with the help of a yaw rate signal or a rotational rate signal.
German Published Patent Application No. 196 36 443 describes a system for monitoring sensors in a vehicle. This system includes an arrangement with which identically defined comparison quantities for the sensors are determined for at least two sensors, starting from at least the signals generated by them. Furthermore, the system includes an additional arrangement with which a reference quantity is determined as a function of the comparison quantities at least thus determined. Starting from at least the reference quantity thus determined, monitoring is performed in a monitoring arrangement for at least one sensor. In addition to the monitoring arrangement, the system also includes an arrangement with which the signal generated by it is corrected for at least one sensor, at least as a function of the reference quantity.
The present invention relates to a device for determining an offset value which represents the offset of the output signal of a vehicle sensor, the sensor detecting at least one motion of a vehicle, and the output signal is analyzed at at least two different points in time. An example embodiment of the present invention is characterized in that
an additional signal is determined independently of the output signal, this signal also representing the motion of the vehicle, and
an arrangement is provided for analyzing the characteristic of the output signal, which depends on the longitudinal velocity of the vehicle, and the characteristic of the additional signal, which also depends on the longitudinal velocity of the vehicle, in order to determine the offset value.
This may permit the most accurate possible determination of the offset value. Since the longitudinal velocity of the vehicle normally changes frequently when driving, it may be advantageous to analyze the characteristic of the output signal, which depends on the longitudinal velocity of the vehicle, and the characteristic of the additional signal, which also depends on the longitudinal velocity of the vehicle.
An example embodiment is characterized in that additional quantities representing the motion of the vehicle are detected, and the additional signal is determined as a function of the additional quantities representing the motion of the vehicle. This may make it possible to access quantities that are detectable with a high accuracy and stability. This is of direct benefit to the accuracy and stability of the method according to the present invention.
The additional quantities representing the motion of the vehicle may include quantities representing the transverse dynamics of the vehicle and/or rotational speed quantities representing the wheel rotational motion of at least two vehicle wheels.
The quantities representing the transverse dynamics of the vehicle may include the steering angle and/or the transverse acceleration of the vehicle. This is because these quantities are already detected by sensors in modern vehicles. It is thus possible to implement the-present invention without any significant expenditure for sensors.
The vehicle sensor is a sensor which detects at least one motion of a vehicle. The output signal is analyzed at at least two different points in time. The characteristic of the output signal, which depends on the longitudinal velocity of the vehicle, may be analyzed to determine the offset value.
In an example embodiment, the characteristic, which depends on the longitudinal velocity of the vehicle, of the difference between the output signal and a reference signal derived from wheel speeds is analyzed as a function of to determine the offset value.
For example, the vehicle sensor may be a rotational rate sensor which detects the yawing motion of the vehicle. The offset value determined may be used, for example, for automatic distance regulation and/or control (ACC) in the motor vehicle.
An additional signal also representing the motion of the vehicle may be determined independently of the output signal of the vehicle sensor. Rotational speed quantities representing the wheel rotational motions of at least two vehicle wheels may be detected, and the additional signal may be determined as a function of these rotational speed quantities.
The output signal of the vehicle sensor may be linked with the additional signal to form a linked signal, and it may be provided that the difference between the signals is formed. The characteristic of the linked signal, which depends on the longitudinal velocity of the vehicle, may be analyzed to determine the offset value.
The offset value may be determined by analyzing at least one property of a regression line in an x-y diagram. In this x-y diagram, the longitudinal velocity of the vehicle is plotted on one axis and the linked signal is plotted on the other axis.
At least one analyzed property of the regression line is the axis intercept on the axis on which the quantity obtained from the analyses of the output signal is plotted. This axis intercept of a line is numerically determinable in a simple manner, thus making the method uncomplicated and stable.
In addition, the slope of the regression line in the x-y diagram may be determined, and another quantity which influences the motion of the vehicle is determined from the slope thus determined. The slope of a line is numerically determinable using a simple arrangement.
The offset value of the output signal of the vehicle sensor may be determined from the axis intercept of the regression line, and it is possible to determine differences in the wheel radii of the non-driven wheels from the slope of the regression line. The determination of the differences in the wheel radii results in a considerable number of additional uses of the present invention.
An example embodiment of the present invention is illustrated in the following drawing and explained in greater detail in the following description.